[18a-C202-1~12] 17.2 Graphene

▼ [18a-C202-4] Evolution of p_z orbital with out-of-plane electric field in bilayer graphene

〇(D)Afsal Kareekunnan¹, Manoharan Muruganathan¹, Hiroshi Mizuta^1,2 (1.JAIST, 2.Hitachi Camb. Lab.)

Keywords:bilayer graphene, out-of-plane electric field, pz orbitals

An out-of-plane electric field can induce band gap in bilayer graphene (BLG) by introducing asymmetry between the top and bottom layers. The immediate impact of the external electric field reflects on the low energy bands such as valence band maximum (VBM) and conduction band minimum (CBM). Hence these two bands take a crucial role in the electronic properties of BLG. As is well known, the major contribution to the VBM and CBM comes from the out-of-plane p_z rbitals of individual C atoms. Thus herein, we investigate the evolution of p_z orbital with the out-of-plane electric field. We observe that, in the case of the VBM magnitude the p_z orbitals on the top layer of BLG shrink with the electric field and disappears at higher fields. As a consequence, the magnitude of the bottom orbitals increase. The CBM also shows the same behavior, but with a change in the role of the layers, as anticipated. This can be ascribed to the polarization of the orbitals in the presence of the electric field.